High Capacity Mg Batteries Based on Inert and Non-Nucleophilic Carborane Electrolytes

非技术摘要在过去的十年里，可充电便携式设备和电动汽车的技术进步呈爆炸式增长。然而，由最先进的锂离子技术提供的降低成本、提高可持续性和增加存储容量的创新并没有跟上这场革命的步伐。此外，锂离子电池可能会发生灾难性的故障，从而导致不可预测的火灾。镁电池是锂离子系统的一个有吸引力的替代品，因为镁更便宜，更丰富，本质上更安全，可以储存两倍的电荷量。在材料研究部固态和材料化学项目的支持下，该项目将开发比传统锂离子系统更强大、更具成本效益的镁电池。该项目的一个关键推动因素是实施了由碳和硼原子集合组成的特殊电解液，称为碳硼烷。加州大学河滨分校(UCR)化学系的本科生和研究生在这个项目中接受指导，并参与研究。此外，首席调查员(PI)和合作PI将一项导师计划纳入了针对贫困高中生的项目。在夏季的几个月里，这些高中生会参加加州大学伯克利分校的拟议研究。这些活动的预期结果是STEM领域招收和留住人数不足的学生的人数增加。技术摘要镁电池是锂离子系统的一种有吸引力的替代品，但缺乏合适的电解液。镁电池的电解液必须完全耐分解，理想情况下不亲核。该项目的目标是生产比最先进的锂离子技术更便宜、更安全、更可持续和更强大的镁电池。这项工作的一个关键特点是实现了惰性和非亲核碳硼烷基电解液，这将使高容量镁电池的实现成为可能。该项目将通过三个具体目标来完成。目的1利用新的化学还原方法制备简单的阳离子镁碳硼烷盐无卤电解液。由于碳硼烷阴离子具有高度的氧化稳定性和非亲核性，因此它们适合用作采用高压插层或S阴极的体系的镁电池电解液。目标2包括具有支持配体的单阳离子碳硼烷电解质的设计。新的转金属方法的实施允许获得含有碳硼烷反阴离子的单阳离子镁络合物，这些阴离子是高压插层阴极的合适电解液。此外，N-杂环卡宾(NHCS)与S8反应生成的硫相容“钝化”电解液的制备也在研究中。在目标3中，将在目标1和目标2中制备的电解液与合适的正极材料偶联，以生产可充电镁电池的原型。层状的钼和钒硫化物以及硫尖晶石的钒和铬硫化物都被用作嵌入型阴极。此外，基于两种不同孔径的碳载体的硫-碳复合材料的硫阴极也在研究中。

Non-Technical AbstractOver the last decade there has been an explosion of technological advances in rechargeable portable devices and electric vehicles. However, innovations that reduce the cost, improve the sustainability, and increase the storage capacity offered by state-of-the-art Li-ion technology have not kept pace with this revolution. In addition, Li-ion batteries can undergo catastrophic failure, which results in unpredictable fires. Mg-based batteries are an attractive alternative to Li-ion systems because Mg is less expensive, much more abundant, inherently safer, and can store twice the amount of charge. With the support from the Solid State and Materials Chemistry program in the Division of Materials Research, this project will develop Mg-batteries that are more powerful and cost effective than traditional Li-ion systems. A key enabling factor of this project is the implementation of special electrolytes composed of collections of carbon and boron atoms called carboranes. Undergraduate and graduate students in the Chemistry Department at the University of California Riverside (UCR) are mentored in this program and participate in research. Additionally, the Principal Investigator (PI) and Co-PI have integrated a mentorship program into the project for disadvantaged high school students. In the summer months, these high school students participate in the proposed research at UCR. The anticipated outcome of these activities is the increased recruitment and retention of students from underrepresented groups in STEM fields.Technical AbstractMg-based batteries are an attractive alternative to Li-ion systems, but suitable electrolytes are lacking. Electrolytes for Mg batteries must be completely resistant to decomposition and ideally non-nucleophilic. The goal of this project is to produce Mg-based batteries that are less expensive, inherently safer, more sustainable and powerful than state-of-the-art-Li-ion technology. A key feature of this work is implementing inert and non-nucleophilic carborane based electrolytes, which will enable the realization of high capacity Mg-batteries. This project will be accomplished via three specific aims. Aim 1 utilizes novel chemical reduction methodology to prepare halide free electrolytes of simple dicationic Mg carborane salts. Because the carborane anions are both highly oxidatively stable and non-nucleophilic, they are suitable for applications as Mg battery electrolytes for systems that utilize either high voltage intercalation or S cathodes. Aim 2 encompasses the design of monocationic carborane electrolytes featuring supporting ligands. Implementation of novel transmetalation methodology allows access to monocationic Mg complexes that contain carborane counter anions, which are suitable electrolytes for high voltage intercalation cathodes. In addition, the preparation of sulfur compatible "passivated" electrolytes derived from the reaction of N-Heterocyclic Carbenes (NHCs) with S8 is under investigation. In Aim 3, the electrolytes prepared in Aims 1 and 2 are coupled with suitable cathode materials to produce prototype rechargeable Mg-batteries. Both layered molybdenum and vanadium sulfides as well as thiospinel vanadium and chromium sulfides are utilized as intercalation type cathodes. In addition, sulfur cathodes based on sulfur-carbon composites with two types of carbon hosts having distinctly different pore sizes are under investigation.